Portable radio communications are widely used to enable coordination between spaced apart users, such as policemen, fireman, or military personnel, for example. U.S. Pat. No. 2,576,128 to Lense issued Nov. 27, 1951 discloses an early version of a manpack antenna, such as for a soldier, that is in the form of a dipole including upper and lower dipole elements. These elements are centrally fed adjacent the waist of the user and extend upwardly toward the user's shoulder and downwardly to the user's knee. Such a large antenna may simply be too unwieldy for many applications.
A more advanced type of portable radio is known as the mini-manpack radio, such as the RF-5800V-HH VHF radio offered by Harris RF Communications Division of Rochester, N.Y. The five watt output mini-manpack handheld radio may be carried on a rear pack of the user. A conventional blade antenna extends upwardly from the radio. The user removes the radio from the pack and holds the radio in his hand during use.
In other similar portable radios, a short flexible rubber duck antenna may be used, however, performance may not be as good as with the blade antenna. Thales Defence Communications of the United Kingdom offers the Panther P (BCC 69) VHF frequency hopping secure EPM transceiver with such a relatively short rubber duck antenna. A long whip antenna may provide better performance, but may be unwieldy for the user. Accordingly, the blade antenna has served as a good compromise. Unfortunately, all these antenna types require a counterpoise provided by the radio itself. In addition, electromagnetic noise from interferers may limit sensitivity of the receiver of the radio.
Other approaches have been described for providing an antenna that is wearable by a user. For example, U.S. Pat. No. 6,590,540 to Adams et al. discloses RF elements attached to a garment so that the RF elements each form a band when the garment is worn. A shorting strap electrically connects the first and second RF elements on the back side of the garment. Unfortunately, such an antenna may not be suitable for longer range communications.
U.S. Pat. No. 4,730,195 to Phillips et al. discloses a shortened wideband antenna sleeve dipole antenna including a helically wound upper radiating element and an inductively loaded lower radiating sleeve element to reduce the linear size of the antenna. A helically wound feed coaxial transmission line is within the sleeve element. A matching network at the antenna feed point provides capacitive reactance above the antenna resonant frequency and inductive reactance below the antenna resonant frequency so that an impedance match is made between the feed coaxial transmission line and dual band performance is obtained.
U.S. Pat. No. 5,949,383 to Hayes et al. discloses an antenna formed on a substrate and including a center feed point. The feed section includes an RF input line and a ground line extending along the substrate and a balun extends along the substrate between the first radiating element and the ground line. Such an antenna may be not meet the durability requirements to be worn by a user or have sufficient power handling capability for longer range communication.